Quick question on speed control repair UPDATE - FIXED!

Yes - you can splice a small section of wire in the tach reader line, but do not try and solder it at the tach reader unless you have some way to clamp the tach reader, have a good magnifier glass and very small soldering iron tip to do very precise soldering.  If you splice the line, make sure you get a good joint and shrink wrap the connections.

Bruce

If the metal wire, itself, is still intact and it's just a case of the vinyl coating having worn off exposing the bare wire, you could try using some liquid electrical tape, applied very carefully (it's messy stuff) to seal the wire.

• Thanks for the quick response, Bruce, Richie. The orange colored coating of the wire that leads to the tach reader seems removed at the point it chaffed under the motor, but the metal wire  part still seems unbroken.  However, I cut and spliced on  a piece of wire at the part where the wire was exposed Just to see if the cruise control worked. It still seems to take off at full speed even at 1smph.  Using the z-4000 handles is the only way to slow it down or speed it up.  My fear is that something shorted out when the coating rubbed off exposing the metal part of the wire.  I was thinking the tach reader might now be broken or the part of the board that receives the orange wire from the tach reader.  Any  thoughts on whether this is something a layman can fix? 

You could have cooked the tach reader.  If you change that and it still happens, the likely suspect is the PS32 board assembly.

There are a couple of parts that can get toasted if you ground things, U67 or R358 are the top suspects.  Obviously, these are small surface mount parts, so you may not be able to repair this yourself.

With a PS-32 board the top board does do some buffering.  May be tach reader, could be open wire.  Could be top board which has chip for PS-2 tach.  Just need to work through it.  But if tach wire signal return grounded to chassis that gets AC on it so the chances the reader is damaged is high.

Thanks Gunrunner and GGG.  Hopefully it’s just the tach reader. Is this something that a non mth tech can replace? If so, Do I go to the mth website to order one of these and are they expensive?  Do you know the part number for a ps-32 tach reader that is appropriate for this model subway (or is this just a standard part?)

Strap Hanger posted:

I do not want to bring this back to the tech repair guy and would prefer trying to fix this myself, if possible.  Any one else experience this and successfully repair it? Thanks for any suggestions/ thoughts. 

 

If it were reassembled with a pinched wire it would be his fault.  I sure as hxxx would take this up with him before trying any repairs yourself.      Was it a MTH approved service station who did your upgrade ?    I am afraid you harmed your cause a bit by opening the unit up yourself. The fact that it ran over a year after the upgrade is not in your favor either. I would however take this up with the repairman before attempting to repair it yourself. Part of his job description is to not pinch wires.    j

In reviewing your thread, I see you have the PS32 board, so there are a number of tach readers you might have, they're all similar with the exception of the way the sensor is mounted.

How about a picture of your tach reader from the side?

Here it is. You can see the orange wire that was pinched in the photos as well. 

Looks like you'll need AG-0000033 Tach Reader board (no spacer), they're $7.

That wire grounded certainly cooked something, hopefully it's only the sensor.

JohnActon posted:

Strap Hanger posted:

I do not want to bring this back to the tech repair guy and would prefer trying to fix this myself, if possible.  Any one else experience this and successfully repair it? Thanks for any suggestions/ thoughts. 

 

If it were reassembled with a pinched wire it would be his fault.  I sure as hxxx would take this up with him before trying any repairs yourself.      Was it a MTH approved service station who did your upgrade ?    I am afraid you harmed your cause a bit by opening the unit up yourself. The fact that it ran over a year after the upgrade is not in your favor either. I would however take this up with the repairman before attempting to repair it yourself. Part of his job description is to not pinch wires.    j

John, you’re right. The tech, who is mth authorized, failed to secure the wire properly and it became pinched under the motor. It’s clearly his fault and it failed within one year.  However, this was the least of my problems with this guy. He tried to use the wrong speaker (the one that came with the upgrade kit and not the special small one designed for this subway) and forced it onto this subway train, bending the frame. When I pointed that out to him, he complained about having to buy a different speaker.  Then he broke one of the mechanical doors and one of the plastic frame pieces when reinstalling the shell.  He tried glueing the frame piece back and made a mess of the underside of the engine.  The headlights were also installed wrong and didn’t work at first. After four visits and returns, he finally got it too work, but I swore I’d never go back to this guy. He is more of a used car mechanic than a delicate train repairman. It’s just not worth it to me and I consider it a lesson learned. 

gunrunnerjohn posted:

Looks like you'll need AG-0000033 Tach Reader board (no spacer), they're $7.

That wire grounded certainly cooked something, hopefully it's only the sensor.

Thanks Gunrunner. I’ll order it and give it a try. For $7, it’s worth a try. Like you said, hopefully it’s just the reader and not something else on the main boards. 

Strap Hanger posted:

John, you’re right. The tech, who is mth authorized, failed to secure the wire properly and it became pinched under the motor. It’s clearly his fault and it failed within one year.  However, this was the least of my problems with this guy. He tried to use the wrong speaker (the one that came with the upgrade kit and not the special small one designed for this subway) and forced it onto this subway train, bending the frame. When I pointed that out to him, he complained about having to buy a different speaker.  Then he broke one of the mechanical doors and one of the plastic frame pieces when reinstalling the shell.  He tried glueing the frame piece back and made a mess of the underside of the engine.  The headlights were also installed wrong and didn’t work at first. After four visits and returns, he finally got it too work, but I swore I’d never go back to this guy. He is more of a used car mechanic than a delicate train repairman. It’s just not worth it to me and I consider it a lesson learned. 

Maybe authorized, but obviously not competent.   That's not to say that any of us never screws something up, but I like to think I have never let anything like that out of the shop!

Strap Hanger posted:

gunrunnerjohn posted:

Looks like you'll need AG-0000033 Tach Reader board (no spacer), they're $7.

That wire grounded certainly cooked something, hopefully it's only the sensor.

Thanks Gunrunner. I’ll order it and give it a try. For $7, it’s worth a try. Like you said, hopefully it’s just the reader and not something else on the main boards. 

It's quite possible that it would be a repairable part if it's on the board, usually these kinds of mishaps take out the op-amp for the tach signal if something gets zapped on the board.  I replaced a few of these on PS/2 boards.

gunrunnerjohn posted:

Strap Hanger posted:

gunrunnerjohn posted:

Looks like you'll need AG-0000033 Tach Reader board (no spacer), they're $7.

That wire grounded certainly cooked something, hopefully it's only the sensor.

Thanks Gunrunner. I’ll order it and give it a try. For $7, it’s worth a try. Like you said, hopefully it’s just the reader and not something else on the main boards. 

It's quite possible that it would be a repairable part if it's on the board, usually these kinds of mishaps take out the op-amp for the tach signal if something gets zapped on the board.  I replaced a few of these on PS/2 boards.

Good to know, Gunrunner. I’ll order the tach reader and give it a try. If that fails, do you take deliveries for repairs? 

Yep, let's see how you make out with the tach reader.  Oh, BTW, fix that wire before you test again.

Will do gunrunner. THanks!

Well I called up Bill Lucas at ready to roll, the best train shop down here in Miami, and he said he had a spare tach reader that was the same model recommended by Gunrunner John. So I drove there today and picked it up. After carefully removing the old one, I soldered on the new one and repaired the broken wire.  As mentioned, the soldering required very careful application and took about 30 minutes to get all three wires secure.  However, thanks to gunrunner johns help, I was able to get my prized subway train back to operating with speed control  and station stops!  Fortunately, it was only the tach reader that burned out and not something on the main board.  Thanks for taking the time to help out a fellow forum member, gunrunner. Much appreciated.  Here is a short video of it running at 3 smph after I was able to carefully put  the shell back on without breaking the manual doors - 

You escaped the cheap way, that's great!